On August 4, 2025, public health officials in San Antonio confirmed the first local detection of West Nile Virus for the season after a mosquito trap near the intersection of West Avenue and Blanco Road tested positive. The sample, collected earlier in the week, underwent testing and confirmation by a laboratory. In response, the city’s Metropolitan Health District announced targeted pesticide spraying in the surrounding area, beginning in the early morning hours of August 6. Officials urged residents in the affected neighborhoods to remain indoors during spraying operations, which are subject to rescheduling depending on weather conditions.
This confirmation in San Antonio is part of a broader and increasingly concerning pattern of mosquito-borne virus activity throughout Texas. Just days before the San Antonio announcement, Hays County reported its first human case of West Nile virus for 2025. In a separate case, Wilson County reported a blood donation that tested positive for both West Nile and Zika viruses. These developments suggest a heightened risk level in the region as the state grapples with the ongoing threat of mosquito-transmitted illnesses during peak season.
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Texas has historically been among the hardest-hit states when it comes to West Nile virus. In 2024, the Texas Department of State Health Services documented 169 confirmed human cases statewide. In addition to those clinical infections, 97 blood donations tested positive, representing a major concern for blood safety and transfusion recipients. Several of those cases, including some from Bexar County, progressed to serious complications involving the nervous system. These neuroinvasive cases can lead to conditions such as meningitis, encephalitis, or acute flaccid paralysis, with long-term health consequences in some patients.
According to the Centers for Disease Control and Prevention, approximately one in four people infected with the virus may develop mild symptoms, including fever, headache, body aches, joint pain, and fatigue. However, less than one percent of those infected will develop severe neurological illness. These complications are most common in older adults, individuals with compromised immune systems, or those with preexisting health conditions.
In light of the risks, San Antonio’s Metropolitan Health District continues to operate a comprehensive vector surveillance and mosquito control program from spring through the fall. As part of its protocol, traps are strategically placed across the city to monitor mosquito activity and identify potential hotspots. When a positive sample is found, response teams are mobilized to conduct ground spraying, which includes both public and private properties within a designated radius of the detection site. Crews also engage in larvicide treatments and provide public outreach to educate residents about reducing mosquito habitats.
Officials continue to stress the importance of individual preventive measures, which they say remain the most effective tools in limiting virus spread. Residents are encouraged to wear long-sleeved clothing and pants, especially at dawn and dusk when mosquito activity is highest. Insect repellents containing DEET, picaridin, or oil of lemon eucalyptus are recommended for daily use. Homeowners are also asked to regularly inspect their properties for sources of standing water—such as flower pots, pet bowls, birdbaths, clogged gutters, or discarded tires—which serve as prime breeding grounds for mosquitoes.
The detection in San Antonio follows a wider pattern being observed in other central Texas counties. Travis County has also reported multiple mosquito pools testing positive for West Nile virus this season, particularly in ZIP codes with higher vegetation density and water exposure. In Austin, health officials have ramped up educational campaigns and mosquito treatment activities in parks and residential zones, warning that this year’s weather patterns—marked by early summer rains and high humidity—have created optimal conditions for mosquito proliferation.
The increasing number of cases and positive tests across the region have prompted renewed calls for public awareness and early intervention. While there is currently no vaccine or specific antiviral treatment for West Nile virus, early detection and medical support can mitigate the severity of symptoms. Health authorities have also urged residents to seek medical attention if they experience persistent high fever, confusion, neck stiffness, or muscle weakness—symptoms that could signal the onset of a more severe infection.
City officials emphasized that controlling the mosquito population is a shared responsibility between public agencies and the community. They underscored the need for continued cooperation and vigilance throughout the summer and early fall months, when the risk of transmission is highest. Residents are also advised to stay informed by monitoring official city announcements and health department updates regarding treatment schedules and virus activity.
With the August detection now confirmed, San Antonio becomes one of several Texas cities facing early-season West Nile concerns in 2025. The next few weeks will be critical in determining whether the virus remains contained or continues to spread, particularly as weather conditions and human outdoor activity intersect during the peak of summer. The city’s response—combined with resident awareness and precaution—will play a central role in shaping the public health outcomes of the current mosquito season.
